Biometric authentication of a user

ABSTRACT

The present invention relates to an electronic device. In particular, the present invention relates to an electronic device comprising a first and a second biometric sensor and processing circuitry arranged to authenticate the user of the electronic device. The present invention also relates to a corresponding method and computer program for authenticating the user of an electronic device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Sweden Application No. 1651702-1,filed on Dec. 21, 2016, the disclosure of which is incorporated hereinby reference in its entirety

TECHNICAL FIELD

The present invention relates to an electronic device. In particular,the present invention relates to an electronic device comprising a firstand a second biometric sensor and processing circuitry arranged toauthenticate the user of the electronic device. The present inventionalso relates to a corresponding method and computer program forauthenticating the user of an electronic device.

BACKGROUND OF THE INVENTION

Various types of biometric systems are used more and more in order toprovide an increased security for accessing an electronic device and atthe same time keep the user convenience at an acceptable level. Inparticular fingerprint sensors have been successfully integrated in suchdevices, for example, thanks to their small form factor, highperformance and user acceptance.

In a fingerprint sensor, a captured image is compared to one or morestored fingerprint templates in order to verify the identity of theuser. In order to avoid performing matching on an image which is of lowquality, where it is likely that no successful matching can beperformed, a quality metric is assigned to the captured image beforematching to determine if the specific image should proceed to thematching step.

However, some people may have difficulties in using the fingerprintsensor, due to having so-called “difficult fingers”. For example, thecharacteristics of the fingerprint may be of generally low quality, i.e.fingerprint image contains low level fingerprint data. Alternatively,the fingerprint pattern may be difficult to detect due to a temporarilymoisturized or dried-out finger.

When the fingerprint sensor is unable to properly match the capturedimage of the fingerprint with the one or more stored fingerprinttemplates, the user of the electronic device is often directed toprovide a personal pin code for e.g. unlocking the electronic device.This has the effect that the fingerprint sensor cannot be sufficientlyused. This may reduce the overall quality feel of the fingerprintsensor.

Accordingly, it is desirable to improve the usability of the fingerprintsensor.

SUMMARY OF THE INVENTION

In view of above-mentioned and other drawbacks, it is an object of thepresent invention to improve the authentication process of a user of anelectronic device.

According to a first aspect of the invention, there is provided anelectronic device, comprising a first biometric sensor arrangement foracquiring a first set of biometric data of a user of the electronicdevice, the first biometric sensor arrangement comprising a fingerprintsensor having an array of pixels and configured for capturingfingerprint data of a fingerprint pattern of a finger of the user of theelectronic device, wherein the fingerprint data represents the first setof biometric data; a second biometric sensor arrangement for acquiring asecond set of biometric data of the user of the electronic device, thesecond biometric sensor arrangement comprising a sensor being differentfrom the sensor comprised with the first biometric sensor arrangement,and processing circuitry connected to the first and the second biometricsensor arrangement, wherein the processing circuitry is configured toacquire the first set of biometric data from the first biometric sensorarrangement; determine a first biometric matching level by comparing thefirst set of biometric data and an enrolled fingerprint of the finger ofthe user; compare the first biometric matching level with a first and asecond threshold, wherein the second threshold corresponds to a highermatching level as compared to the first threshold; acquire, only if thefirst biometric matching level is above the first threshold but belowthe second threshold, the second set of biometric data from the secondbiometric sensor arrangement; determine a second biometric matchinglevel by comparing the second set of biometric data and an enrolled userrepresentation corresponding to the sensor comprised with the secondbiometric sensor arrangement; determine a third matching level based onthe first and the second matching level, and authenticate the user ofthe electronic device if the third matching level is above a thirdthreshold, wherein the third threshold corresponds to a higher matchinglevel as compared to the second threshold.

An enrolled fingerprint should be understood to correspond to thefingerprint data of the user's finger which the user “previously”provided when activated/registered himself with the fingerprint sensor.Hence, the enrolled fingerprint corresponds to the fingerprint, orfingerprints, of the user of the electronic device. Within the contextof the present disclosure, the expression “fingerprint data” should beinterpreted broadly and to include both a regular “visual image” of afingerprint of a finger as well as a set of measurements relating to thefinger when acquired using the fingerprint sensor. A plurality offingerprint images may be subsequently acquired and fused together,where the resulting information is used as an input for determining thesets of features. Similarly, the “enrolled user representationcorresponding to the sensor comprised with the second biometric sensorarrangement” corresponds to previously acquired biometric data at whichthe user activated/registered the specific second biometric sensorarrangement. Furthermore, the second biometric sensor arrangement isdifferent in comparison to the first biometric sensor arrangement. Thesecond biometric sensor arrangement is thus not a fingerprint sensorarrangement. Various alternatives of second biometric sensorarrangements are described in further detail below.

The different thresholds, i.e. the first, second and third thresholds,may be different for different applications. For example, the firstthreshold is generally low and is arranged to determine if it is afinger that is positioned on the fingerprint sensor. Hence, if the firstbiometric matching level is above the first threshold, it is determinedthat a finger is positioned on the fingerprint sensor. Thereafter, ifthe first biometric matching level is in the range between the first andsecond thresholds, i.e. below, or at the second threshold, the detectedfingerprint can not sufficiently authenticate the user of the electronicdevice. This may be caused by a difficult finger as mentioned above, oras a result of e.g. a temporarily slightly moisturized or wet finger, ora temporarily dry finger.

Moreover, the expression “processing circuitry” should be understood toinclude any type of computing device, such as an ASIC, amicro-processor, etc. It should also be understood that the actualimplementation of such a processing circuitry may be divided betweenmore than a single device/circuit.

The present invention is based on the insight that by using a secondbiometric sensor arrangement, in combination with the first biometricsensor arrangement, i.e. two different systems, a first and a secondmatching level can be determined for each of the two different systems.Based on the first and second matching levels, e.g. combining the firstand second matching levels, a third matching level can be determined.Hence, the first and second matching levels are e.g. fused to form thethird matching level, which third matching level is compared to a thirdthreshold being higher in comparison to the second threshold. The thirdmatching level may naturally depend on the technology applied by thesecond biometric sensor arrangement, e.g. the third matching level maybe a ratio of the first and second matching levels. Hereby, ifinsufficient fingerprint data is acquired by the fingerprint sensor,further biometric data acquired by the second biometric sensorarrangement can, in combination with the fingerprint data be used toauthenticate the user of the electronic device. An advantage is thusthat the user of the electronic device will be able to use thefingerprint sensor to a larger extent, and get assistance from thesecond biometric sensor arrangement in those cases where the fingerprintdata from the fingerprint sensor is insufficient to fully authenticatethe user. Hereby, the user will not have to be instructed to provide thePIN code whenever e.g. the finger is temporarily moisturized or wet.

The sensor of the second biometric sensor arrangement may, for example,be a sensor for allowing an iris scan of the user to be performed, or asensor for allowing a face recognition of the user to be performed. Thesensor may, for example, be a camera or an IR scanning device. Accordingto a further and preferred embodiment, the sensor of the secondbiometric sensor arrangement may be a motion sensor for providing senseddata based on movement of the electronic device in space. In such anembodiment, the enrolled user representation corresponding to the sensorcomprised with the second biometric sensor arrangement may be anenrolled gesture performed by the user when moving the portableelectronic device in space. Such a sensor may comprise at least oneaccelerometer.

Hereby, when the user positions the finger on the fingerprint sensor,and executes a motion of the electronic device, the third matching levelis generated and can thus be compared to the third threshold forauthentication of the user. In an exemplified implementation, when theuser positions his finger on the fingerprint sensor and it is determinedthat the first matching level is in the range between the first andsecond thresholds, i.e. the acquired fingerprint data is notsufficiently good to authenticate the user, the user can, whilepreferably maintaining the finger on the fingerprint sensor, perform agesture by moving the electronic device in space. If the detectedgesture in combination with the detected fingerprint together provides athird matching level which is above the third threshold, the user can beauthenticated as the authorized user of the electronic device. Anadvantage of using a motion sensor is that the biometric data for such abiometric sensor can be rather easily acquired, especially if theelectronic device is portable. Hereby, the user only needs to e.g.“shake” the electronic device while preferably but optionally keepingthe finger on the fingerprint sensor. The movement may also correspondto an angular position or angular movement of the electronic device,which angular position/movement is/are previously enrolled by the user.Hereby, the user will be provided with a feel as no additional action isrequired for authentication.

In a preferred embodiment, the level of the second threshold may bedependent on the technology applied by the second biometric sensorarrangement. As a gesture of the user may involve uncertainty incomparison to e.g. an iris scan, the second threshold should preferablybe set higher when using a motion sensor in comparison to when using asensor for allowing the iris scan. Accordingly, when setting a highersecond threshold, the requirement of the detected fingerprint is higherin comparison to a lower second threshold when fusing the first andsecond matching levels for authenticating the user.

Moreover, the first, the second and the third threshold may be based ona so-called false acceptance rate (FAR). This is a rate determining howmuch “fault” is accepted. A lower FAR corresponds to a higher“correctness” of the biometric data in comparison to its enrolled datain comparison to a higher FAR. The FAR of the second threshold may thusbe determined by the technology applied by the second biometric sensorarrangement. According to non-limiting examples, the first FAR thresholdmay be at least 1:100, the second FAR threshold may be at least 1:1000and the third FAR threshold may be at least 1:50000.

According to an example embodiment, the second set of biometric data maybe acquired from the second biometric sensor arrangement only if theuser's finger is arranged at the fingerprint sensor for a completeduration of the acquisition of the second set of biometric data.

Also, according to an example embodiment, the electronic device mayfurther comprise a third biometric sensor arrangement for acquiring athird set of biometric data of the user of the electronic device, thethird biometric sensor arrangement comprising a sensor being differentfrom the sensors comprised with the first and the second biometricsensor arrangement. The sensors of the second and the third biometricsensor arrangement may comprise a motion sensor and a camera. Hereby, afurther sensor can assist in authenticating the user of the electronicdevice according to the principle of the invention described above.

The fingerprint sensor may in one embodiment be a fingerprint touchsensor, e.g. employing at least one of ultrasonic and capacitive sensingtechnology. These fingerprint sensors may be advantageous in that theycan be made relatively small and energy efficient while being able toidentify a fingerprint with high accuracy. However, the above describedembodiments can equally as well be implemented and provide advantagesusing other types of fingerprint sensors as well (e.g. swipe) andemploying different sensing technology such as including e.g. opticalfingerprint sensors, etc.

Furthermore, according to an example embodiment, the electronic devicemay be portable. For example, the electronic device may be at least oneof a mobile phone, a wearable device, a stylus, a tablet and a laptop.

According to a second aspect of the present invention, there is provideda method of authenticating a user of an electronic device, theelectronic device comprising a first biometric sensor arrangement foracquiring a first set of biometric data of a user of the electronicdevice, the first biometric sensor arrangement comprising a fingerprintsensor having an array of pixels and configured for capturingfingerprint data of a fingerprint pattern of a finger of the user of theelectronic device, wherein the fingerprint data represents the first setof biometric data; a second biometric sensor arrangement for acquiring asecond set of biometric data of the user of the electronic device, thesecond biometric sensor arrangement comprising a sensor being differentfrom the sensor comprised with the first biometric sensor arrangement,and processing circuitry connected to the first and the second biometricsensor arrangement, wherein the method comprises the steps of acquiringthe first set of biometric data from the first biometric sensorarrangement; determining a first biometric matching level by comparingthe first set of biometric data and an enrolled fingerprint of thefinger of the user; comparing the first biometric matching level with afirst and a second threshold, wherein the second threshold correspondsto a higher matching level as compared to the first threshold;acquiring, only if the first biometric matching level is above the firstthreshold but below the second threshold, the second set of biometricdata from the second biometric sensor arrangement; determining a secondbiometric matching level by comparing the second set of biometric dataand an enrolled user representation corresponding to the sensorcomprised with the second biometric sensor arrangement; determining athird matching level based on the first and the second matching level,and authenticating the user of the electronic device if the thirdmatching level is above a third threshold, wherein the third thresholdcorresponds to a higher matching level as compared to the secondthreshold.

According to a third aspect of the present invention, there is provideda computer program product comprising a non-transitory computer readablemedium having stored thereon computer program means for processingcircuitry adapted for controlling an electronic device, the electronicdevice comprising a first biometric sensor arrangement for acquiring afirst set of biometric data of a user of the electronic device, thefirst biometric sensor arrangement comprising a fingerprint sensorhaving an array of pixels and configured for capturing fingerprint dataof a fingerprint pattern of a finger of the user of the electronicdevice, wherein the fingerprint data represents the first set ofbiometric data; a second biometric sensor arrangement for acquiring asecond set of biometric data of the user of the electronic device, thesecond biometric sensor arrangement comprising a sensor being differentfrom the sensor comprised with the first biometric sensor arrangement,and the processing circuitry, the processing circuitry connected to thefirst and the second biometric sensor arrangement, wherein the computerprogram product comprises: code for acquiring the first set of biometricdata from the first biometric sensor arrangement; code for determining afirst biometric matching level by comparing the first set of biometricdata and an enrolled fingerprint of the finger of the user; code forcomparing the first biometric matching level with a first and a secondthreshold, wherein the second threshold corresponds to a higher matchinglevel as compared to the first threshold; code for acquiring, only ifthe first biometric matching level is above the first threshold butbelow the second threshold, the second set of biometric data from thesecond biometric sensor arrangement; code for determining a secondbiometric matching level by comparing the second set of biometric dataand an enrolled user representation corresponding to the sensorcomprised with the second biometric sensor arrangement; code fordetermining a third matching level based on the first and the secondmatching level, and code for authenticating the user of the electronicdevice if the third matching level is above a third threshold, whereinthe third threshold corresponds to a higher matching level as comparedto the second threshold.

Effects and features of the second and third aspects are largelyanalogous to those described above in relation to any of the embodimentof the first aspect.

Further features of, and advantages with, the present invention willbecome apparent when studying the appended claims and the followingdescription. The skilled person realize that different features of thepresent invention may be combined to create embodiments other than thosedescribed in the following, without departing from the scope of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be describedin more detail, with reference to the appended drawings showing anexample embodiment of the invention, wherein:

FIG. 1 schematically exemplifies an electronic device according to thepresent invention, in the form of a mobile phone comprising anintegrated fingerprint sensor;

FIG. 2 is a schematic illustration of an example embodiment of a firstand a second biometric sensor arrangement connected to processingcircuitry; and

FIG. 3 is a flow chart illustrating an example embodiment of a method ofauthenticating a user according to an example embodiment.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which currently preferredembodiments of the invention are shown. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided for thoroughness and completeness, and fully convey the scopeof the invention to the skilled person. Like reference characters referto like elements throughout.

Turning now to the drawings and to FIG. 1 in particular, there isschematically illustrated the electronic device according to the presentinvention, in the form of a mobile phone 100 with a first biometricsensor arrangement comprising an integrated fingerprint sensor 102 and adisplay unit 104 with a touch screen interface 106. In this embodimentthe fingerprint sensor 102 and the display unit 104 are togetherarranged at the front side of the mobile phone 100. The fingerprintsensor 102 may, for example, be used for unlocking the mobile phone 100and/or for authorizing transactions carried out using the mobile phone100, etc. The fingerprint sensor 102 may of course also be placed on thebackside of the mobile phone 100. The electronic device also comprises asecond biometric sensor arrangement which will be described in furtherdetail below in relation to the description of FIG. 2.

Preferably and as is apparent for the skilled person, the mobile phone100 shown in FIG. 1 further comprises a first antenna for WLAN/Wi-Ficommunication, a second antenna for telecommunication communication, amicrophone, a speaker, and a phone control unit. Further hardwareelements are of course possibly comprised with the mobile phone. Itshould furthermore be noted that the invention may be applicable inrelation to any other type of portable electronic device, such as alaptop, a remote control, a tablet computer, or any other type ofpresent or future similarly configured device.

With reference to FIG. 2 which schematically illustrates an exampleembodiment of the first 202 and second 206 biometric sensorarrangements, and their connection to processing circuitry 214 of theelectronic device. In further detail, the electronic device comprising afirst biometric sensor arrangement 202 comprising a fingerprint sensor102, which in FIG. 2 is conceptually illustrated in a somewhat enlargedview. According to a non-limiting example, the fingerprint sensor 102 isconfigured to comprise a large plurality of sensing elements, preferablyarranged as a two-dimensional array. The two-dimensional array may havesizes depending on the planned implementation and in an embodiment160×160 pixels are used. Other sizes are of course possible and withinthe scope of the invention, including two-dimensional array with lesspixels as compared to the above example. A single sensing element (alsodenoted as a pixel) is in FIG. 2 indicated by reference numeral 204. Thefingerprint sensor 102 is thus arranged to capture an image of thefingerprint of a finger of a user of the electronic device 100. Thefingerprint data is provided to the processing circuitry 214, as will bedescribed further below.

Moreover, and as stated above, the electronic device 100 comprises asecond biometric sensor arrangement 206. The second biometric sensorarrangement 206 is arranged to acquire biometric data being different incomparison to the biometric data of the fingerprint sensor, from theuser of the electronic device 100. The second biometric sensorarrangement 206 thus comprises a sensor which is different in comparisonto the fingerprint sensor 102. FIG. 2 illustrates three differentexemplifying types of sensors that may be used by the second biometricsensor arrangement 206. It should however be understood that other typesof sensors may equally as well be used instead of, or in combinationwith the exemplified sensors in FIG. 2.

According to an example embodiment, the sensor of the second biometricsensor arrangement 206 may be an iris scanning sensor 208 for allowingan iris scan of the user to be performed. The iris scanning sensor 208may form part of a camera of the electronic device 100, such as analready existing camera provided with iris scanning functionality, or anadditional iris scanning camera. The iris scanning sensor may also be anIR scanning device. Hereby, when the user has enrolled his eye(s), theiris scanning sensor 208 can be used as a complement to the fingerprintsensor 102 when authenticating a user of the electronic device.

According to another example embodiment, the sensor of the secondbiometric sensor arrangement 206 may be a face recognition sensor 210for allowing a face recognition of the user to be performed. The facerecognition sensor 210 may form part of a camera of the electronicdevice 100, such as an already existing camera provided with facerecognition functionality, or an additional face recognition camera.Hereby, when the user has enrolled his face, the face recognition sensor210 can be used as a complement to the fingerprint sensor 102 whenauthenticating a user of the electronic device.

According to a still further example embodiment, the sensor of thesecond biometric sensor arrangement 206 may be a motion sensor 212. Themotion sensor 212 is arranged to provide sensed data based on movementof the electronic device 100. In FIG. 2, the sensed motion isillustrated by a pendulum movement of the electronic device 100. Themotion sensor 212 preferably, comprises at least one accelerometer. Theaccelerometer may be an accelerometer already provided in the electronicdevice for also controlling other functionalities of the electronicdevice. The accelerometer may also be an accelerometer specificallydesignated for the sole purpose of assisting the motion sensor 212.

The authorized user of the electronic device 100 thus enrolls the motionsensor 212 by moving the electronic device at a specific motion inspace. The specific motion in space is preferably a user specific motionin space. The user specific motion in space can be a motioncorresponding to a movement when lifting the electronic device from e.g.a table or from the pocket, etc. The user specific motion can also be apredefined gesture, such as a movement of the electronic device in aclockwise circular motion, or a counter-clockwise circular motion, etc.Hence, any type of motions/gestures of the electronic device isconceivable. The motion sensor 212 can hereby be used as a complement tothe fingerprint sensor 102 when authenticating a user of the electronicdevice, by providing substantially the same gesture to the electronicdevice as the enrolled gesture. The following will only describe asecond biometric sensor arrangement 206 comprising the above describedmotion sensor 212.

Moreover, the electronic device 100 also comprises processing circuitry214. The processing circuitry 214 is configured to acquire biometricdata from the first biometric sensor arrangement 202 and the secondbiometric sensor arrangement 206.

The processing circuitry 214 further comprises a memory, such as adatabase, e.g. for storing one or a plurality of fingerprint templatefor one or a plurality of fingers for the user, and one or a pluralityof templates of the second biometric sensor arrangement for the user.The processing circuitry 214 may include a microprocessor,microcontroller, programmable digital signal processor or anotherprogrammable device. The processing circuitry 214 may also, or instead,include an application specific integrated circuit, a programmable gatearray or programmable array logic, a programmable logic device, or adigital signal processor. Where the processing circuitry 214 includes aprogrammable device such as the microprocessor, microcontroller orprogrammable digital signal processor mentioned above, the processor mayfurther include computer executable code that controls operation of theprogrammable device. It should be understood that all or some parts ofthe functionality provided by means of the processing circuitry 214 maybe at least partly integrated with the first biometric sensorarrangement 202 and/or the second biometric sensor arrangement 206.

Accordingly, the processing circuitry 214 acquires a first set ofbiometric data from the first biometric sensor arrangement 202. Hereby,the user of the electronic device 100 seeks to gain access to theelectronic device 100. The processing circuitry 214 determines a firstbiometric matching level by comparing the first set of biometric datawith the enrolled fingerprint of the finger of the user. However, in theevent the fingertip is e.g. slightly moisturized or too dry, e.g. it isa difficult finger, the received fingerprint data may not fullycorrespond to the enrolled fingerprint. The processing circuitry maythus not be able to sufficiently authorize the user solely by using thefirst set of biometric data, i.e. the first matching level is too low.However, the processing circuitry 214 may then in such a case acquire asecond set of biometric data from the second biometric sensorarrangement 206. For example, the user may be advised to provide theuser specific gesture to the electronic device 100. Hereby, the motionsensor 212 provides the sensed data based on the motion in space of theelectronic device 100 to the processing circuitry 214. The processingcircuitry 214 can thereafter compare the received data with enrolleddata of the motion sensor 212 and determine a second biometric matchinglevel.

The processing circuitry 214 can thereafter determine a third matchinglevel which is based on the first and the second matching level. Hereby,e.g. an “almost approved” fingerprint, in combination with a gesturethat is likely to represent the authorized user of the electronic device100, can be used in combination to authenticate the user. In order todescribe the functionality of the processing circuitry 214, and inparticularly the method executed by the processing circuitry 214 forauthenticating a user of an electronic device 100, reference is made toFIG. 3.

Firstly, the processing circuitry 214 acquires S1 a first set ofbiometric data from the first biometric sensor arrangement 202. The userof the electronic device thus positions his finger on the fingerprintsensor 102 and fingerprint data is acquired by the processing circuitry214. By comparing the first set of biometric data and an enrolledfingerprint of the finger of the authorized user, a first biometricmatching level is determined S2. The first biometric matching level isthus a level of correspondence between the fingerprint data and theenrolled fingerprint. The first biometric matching level is thereaftercompared S3 with a first and a second threshold. The first threshold isset lower than the second threshold and provided for determining if itis a finger that is positioned on the fingerprint sensor 102 or not.Accordingly, it is determined S4 if the first biometric matching levelis higher than the first threshold. If the first biometric matchinglevel is lower than the first threshold, it is determined that it is nota finger that is positioned on the fingerprint sensor 102, and noauthentication S11 of the user can be made. On the other hand, if it isdetermined S5 that the first biometric matching level is higher than thefirst threshold and also higher than the second threshold, then user canbe authenticated S10 solely by the received data from the fingerprintsensor 102.

However, if it is determined S5 that the first biometric matching levelis somewhere between the first and second thresholds, i.e. the dataacquired from the fingerprint sensor is determined to be a fingerprintbut it is not sufficient for properly authenticating the user of theelectronic device 100, the processing circuitry 214 acquires S6 a secondset of data from the second biometric sensor arrangement 206. Accordingto the above example with the motion sensor 212, the processingcircuitry 214 acquires a detected gesture by the user of the electronicdevice 100. By comparing this gesture with an enrolled gesture made bythe authorized user of the electronic device 100, a second biometricmatching level is determined S7. Accordingly, the second biometricmatching level is thus a level of correspondence between the gesturedetected by the motion sensor 212 and the enrolled gesture.

By means of the determined first and second matching levels, a thirdmatching level is determined S8. The first and second matching levelsare fused to form the third matching level. Hereby, if the data from thefingerprint sensor is not sufficient to authenticate the user of theelectronic device 100, a combination of the received fingerprint dataand the data of the performed gesture may be used for authorizing theuser. Hereby, the third matching level is compared S9 with a thirdthreshold which is higher than the second threshold. If the thirdmatching level is below the third threshold, then no authentication S11can be made. However, if the third matching level is higher than thethird threshold, the user is authenticated S10.

The third matching level is thus based on the first and second matchinglevels. According to an example embodiment, the third threshold may bebased on the specific type of second biometric sensor arrangement used.Thus, using a second biometric sensor with a relatively high securitylevel for identification, i.e. identification of a user can be made witha relatively high measure of security; the third threshold may be setlower in comparison to the use of a more low security biometric sensorarrangement. A biometric sensor arrangement comprising a sensor for irisscanning can be considered a high level security sensor in comparison toa biometric sensor comprising a motion sensor. Accordingly, a dynamicthird threshold is provided.

According to another example, a first biometric matching level may becompensated depending on the type of second biometric sensor arrangementthat is being used. For example, the difference between the firstbiometric matching level and the second threshold may be higher whenusing a second biometric sensor arrangement with high level of securityin comparison to the use of a second biometric sensor arrangement withlow level of security. In other words, a low match between thefingerprint and the enrolled finger can be compensated by the use of asecond biometric sensor arrangement with a high level of security, whilethe use of a second biometric sensor arrangement with relatively lowlevel of security demands that the matching level is almost at thesecond threshold. In other words, the second threshold may also bedependent on the specific type of second biometric sensor arrangementused, wherein the level of the second threshold is reversed proportionalto the security level of the second biometric sensor arrangement used.Accordingly, a higher second threshold for lower identification securityof the second biometric sensor arrangement, and a lower second thresholdfor increased higher identification security of the second biometricsensor arrangement.

Accordingly, using a difficult finger to gain access to the electronicdevice 100 can be compensated by providing a second set of biometricdata to the processing circuitry 214 for authentication. Hereby, whenusing a difficult finger, the user can still gain access to theelectronic device without the need of e.g. manually providing the pincode to the electronic device 100.

The control functionality of the present disclosure may be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwire system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedium for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROMor other optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Wheninformation is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a machine, the machine properly views theconnection as a machine-readable medium. Thus, any such connection isproperly termed a machine-readable medium. Combinations of the above arealso included within the scope of machine-readable media.Machine-executable instructions include, for example, instructions anddata which cause a general purpose computer, special purpose computer,or special purpose processing machines to perform a certain function orgroup of functions.

Although the figures may show a sequence the order of the steps maydiffer from what is depicted. Also two or more steps may be performedconcurrently or with partial concurrence. Such variation will depend onthe software and hardware systems chosen and on designer choice. Allsuch variations are within the scope of the disclosure. Likewise,software implementations could be accomplished with standard programmingtechniques with rule based logic and other logic to accomplish thevarious connection steps, processing steps, comparison steps anddecision steps. Additionally, even though the invention has beendescribed with reference to specific exemplifying embodiments thereof,many different alterations, modifications and the like will becomeapparent for those skilled in the art.

In addition, variations to the disclosed embodiments can be understoodand effected by the skilled addressee in practicing the claimedinvention, from a study of the drawings, the disclosure, and theappended claims. Furthermore, in the claims, the word “comprising” doesnot exclude other elements or steps, and the indefinite article “a” or“an” does not exclude a plurality.

1. An electronic device, comprising: a first biometric sensorarrangement for acquiring a first set of biometric data of a user of theelectronic device, the first biometric sensor arrangement comprising afingerprint sensor having an array of pixels and configured forcapturing fingerprint data of a fingerprint pattern of a finger of theuser of the electronic device, wherein the fingerprint data representsthe first set of biometric data; a second biometric sensor arrangementfor acquiring a second set of biometric data of the user of theelectronic device, the second biometric sensor arrangement comprising asensor being different from the sensor comprised with the firstbiometric sensor arrangement, and processing circuitry connected to thefirst and the second biometric sensor arrangement, wherein theprocessing circuitry is configured to: acquire the first set ofbiometric data from the first biometric sensor arrangement; determine afirst biometric matching level by comparing the first set of biometricdata and an enrolled fingerprint of the finger of the user; compare thefirst biometric matching level with a first and a second threshold,wherein the second threshold corresponds to a higher matching level ascompared to the first threshold; authenticate the user of the electronicdevice if the first biometric matching level is above the secondthreshold; acquire, only if the first biometric matching level is abovethe first threshold but below the second threshold, the second set ofbiometric data from the second biometric sensor arrangement; determine asecond biometric matching level by comparing the second set of biometricdata and an enrolled user representation corresponding to the sensorcomprised with the second biometric sensor arrangement; determine athird matching level based on the first and the second matching level,and authenticate the user of the electronic device if the third matchinglevel is above a third threshold, wherein the third thresholdcorresponds to a higher matching level as compared to the secondthreshold.
 2. The electronic device according to claim 1, wherein thesensor of the second biometric sensor arrangement is a motion sensor forproviding sensed data based on movement of the electronic device inspace, and the enrolled user representation corresponding to the sensorcomprised with the second biometric sensor arrangement is an enrolledgesture performed by the user when moving the portable electronic devicein space.
 3. The electronic device according to claim 2, wherein themotion sensor comprises at least one accelerometer.
 4. The electronicdevice according to claim 1, wherein the sensor of the second biometricsensor arrangement is a sensor for allowing an iris scan of the user tobe performed.
 5. The electronic device according to claim 1, wherein thesensor of the second biometric sensor arrangement is a sensor forallowing a face recognition of the user to be performed.
 6. Theelectronic device according to claim 4, wherein the sensor comprisedwith the second biometric sensor arrangement is a camera or an IRscanning device.
 7. The electronic device according to claim 1, whereinthe second set of biometric data is acquired from the second biometricsensor arrangement only if the user's finger is arranged at thefingerprint sensor for a complete duration of the acquisition of thesecond set of biometric data.
 8. The electronic device according toclaim 1, further comprising a third biometric sensor arrangement foracquiring a third set of biometric data of the user of the electronicdevice, the third biometric sensor arrangement comprising a sensor beingdifferent from the sensors comprised with the first and the secondbiometric sensor arrangement.
 9. The electronic device according toclaim 8, wherein the sensors of the second and the third biometricsensor arrangement comprises a motion sensor and a camera.
 10. Theelectronic device according to claim 1, wherein the fingerprint sensoris a fingerprint touch sensor.
 11. The electronic device according toclaim 1, wherein the first, the second and the third threshold is basedon a false acceptance rate (FAR).
 12. The electronic device according toclaim 11, wherein the first FAR threshold is at least 1:100.
 13. Theelectronic device according to claim 11, wherein the second FARthreshold is at least 1:1000.
 14. The electronic device according toclaim 11, wherein the third FAR threshold is at least 1:50000.
 15. Theelectronic device according to claim 1, wherein the electronic device isportable.
 16. The electronic device according to claim 1, wherein theelectronic device is at least one of a mobile phone, a wearable device,a stylus, a tablet and a laptop.
 17. The electronic device according toclaim 1, wherein the fingerprint sensor employs at least one ofultrasonic and capacitive sensing technology.
 18. A method ofauthenticating a user of an electronic device, the electronic devicecomprising: a first biometric sensor arrangement for acquiring a firstset of biometric data of a user of the electronic device, the firstbiometric sensor arrangement comprising a fingerprint sensor having anarray of pixels and configured for capturing fingerprint data of afingerprint pattern of a finger of the user of the electronic device,wherein the fingerprint data represents the first set of biometric data;a second biometric sensor arrangement for acquiring a second set ofbiometric data of the user of the electronic device, the secondbiometric sensor arrangement comprising a sensor being different fromthe sensor comprised with the first biometric sensor arrangement, andprocessing circuitry connected to the first and the second biometricsensor arrangement, wherein the method comprises: acquiring the firstset of biometric data from the first biometric sensor arrangement;determining a first biometric matching level by comparing the first setof biometric data and an enrolled fingerprint of the finger of the user;comparing the first biometric matching level with a first and a secondthreshold, wherein the second threshold corresponds to a higher matchinglevel as compared to the first threshold; authenticating the user of theelectronic device if the first biometric matching level is above thesecond threshold; acquiring, only if the first biometric matching levelis above the first threshold but below the second threshold, the secondset of biometric data from the second biometric sensor arrangement;determining a second biometric matching level by comparing the secondset of biometric data and an enrolled user representation correspondingto the sensor comprised with the second biometric sensor arrangement;determining a third matching level based on the first and the secondmatching level, and authenticating the user of the electronic device ifthe third matching level is above a third threshold, wherein the thirdthreshold corresponds to a higher matching level as compared to thesecond threshold.
 19. Computer program product comprising anon-transitory computer readable medium having stored thereon computerprogram means for processing circuitry adapted for controlling anelectronic device, the electronic device comprising: a first biometricsensor arrangement for acquiring a first set of biometric data of a userof the electronic device, the first biometric sensor arrangementcomprising a fingerprint sensor having an array of pixels and configuredfor capturing fingerprint data of a fingerprint pattern of a finger ofthe user of the electronic device, wherein the fingerprint datarepresents the first set of biometric data; a second biometric sensorarrangement for acquiring a second set of biometric data of the user ofthe electronic device, the second biometric sensor arrangementcomprising a sensor being different from the sensor comprised with thefirst biometric sensor arrangement, and the processing circuitry, theprocessing circuitry connected to the first and the second biometricsensor arrangement, wherein the computer program product comprises: codefor acquiring the first set of biometric data from the first biometricsensor arrangement; code for determining a first biometric matchinglevel by comparing the first set of biometric data and an enrolledfingerprint of the finger of the user; code for comparing the firstbiometric matching level with a first and a second threshold, whereinthe second threshold corresponds to a higher matching level as comparedto the first threshold; code for authenticating the user of theelectronic device if the first biometric matching level is above thesecond threshold; code for acquiring, only if the first biometricmatching level is above the first threshold but below the secondthreshold, the second set of biometric data from the second biometricsensor arrangement; code for determining a second biometric matchinglevel by comparing the second set of biometric data and an enrolled userrepresentation corresponding to the sensor comprised with the secondbiometric sensor arrangement; code for determining a third matchinglevel based on the first and the second matching level, and code forauthenticating the user of the electronic device if the third matchinglevel is above a third threshold, wherein the third thresholdcorresponds to a higher matching level as compared to the secondthreshold.